A survey of z ∼ 6 Quasars in the sloan digital sky survey deep stripe. I. A flux-limited sample at zAB < 21

Linhua Jiang, Xiaohui Fan, James Annis, Robert H. Becker, Richard L. White, Kuenley Chiu, Huan Lin, Robert H. Lupton, Gordon T. Richards, Michael A. Strauss, Sebastian Jester, Donald P. Schneider

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Abstract

We present the discovery of five quasars at z 6 selected from 260 deg 2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the celestial equator. The five quasars with 20 < zAB < 21 are 1-2 magnitudes fainter than the luminous z 6 quasars discovered in the SDSS main survey. One of them was independently discovered by the UKIRT Infrared Deep Sky Survey. These quasars, combined with another z 6 quasar known in this region, make a complete flux-limited quasar sample at zAB < 21. The sample spans the redshift range 5.85 ≤ z ≤ 6.12 and the luminosity range -26.5 ≤ M 1450 ≤ -25.4 (H 0 = 70 km s-1 Mpc -1, Ωm = 0.3, and ΩΛ = 0.7). We use the 1/Va method to determine that the comoving quasar spatial density at 〈z〉 = 6.0 and 〈M 1450〉 = -25.8 is (5.0 2.1) × 10-9 Mpc-3 mag-1. We model the bright-end quasar luminosity function (QLF) at z 6 as a power law Φ(L 1450) L β 1450. The slope β calculated from a combination of our sample and the luminous SDSS quasar sample is -3.1 0.4, significantly steeper than the slope of the QLF at z 4. Based on the derived QLF, we find that the quasar/active galactic nucleus (AGN) population cannot provide enough photons to ionize the intergalactic medium (IGM) at z 6 unless the IGM is very homogeneous and the luminosity (L*1450) at which the QLF power law breaks is very low.

Original languageEnglish (US)
Pages (from-to)1057-1066
Number of pages10
JournalAstronomical Journal
Volume135
Issue number3
DOIs
StatePublished - Mar 1 2008

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quasars
luminosity
power law
intergalactic media
slopes
equators
active galactic nuclei

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Jiang, Linhua ; Fan, Xiaohui ; Annis, James ; Becker, Robert H. ; White, Richard L. ; Chiu, Kuenley ; Lin, Huan ; Lupton, Robert H. ; Richards, Gordon T. ; Strauss, Michael A. ; Jester, Sebastian ; Schneider, Donald P. / A survey of z ∼ 6 Quasars in the sloan digital sky survey deep stripe. I. A flux-limited sample at zAB < 21. In: Astronomical Journal. 2008 ; Vol. 135, No. 3. pp. 1057-1066.
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title = "A survey of z ∼ 6 Quasars in the sloan digital sky survey deep stripe. I. A flux-limited sample at zAB < 21",
abstract = "We present the discovery of five quasars at z 6 selected from 260 deg 2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the celestial equator. The five quasars with 20 < zAB < 21 are 1-2 magnitudes fainter than the luminous z 6 quasars discovered in the SDSS main survey. One of them was independently discovered by the UKIRT Infrared Deep Sky Survey. These quasars, combined with another z 6 quasar known in this region, make a complete flux-limited quasar sample at zAB < 21. The sample spans the redshift range 5.85 ≤ z ≤ 6.12 and the luminosity range -26.5 ≤ M 1450 ≤ -25.4 (H 0 = 70 km s-1 Mpc -1, Ωm = 0.3, and ΩΛ = 0.7). We use the 1/Va method to determine that the comoving quasar spatial density at 〈z〉 = 6.0 and 〈M 1450〉 = -25.8 is (5.0 2.1) × 10-9 Mpc-3 mag-1. We model the bright-end quasar luminosity function (QLF) at z 6 as a power law Φ(L 1450) L β 1450. The slope β calculated from a combination of our sample and the luminous SDSS quasar sample is -3.1 0.4, significantly steeper than the slope of the QLF at z 4. Based on the derived QLF, we find that the quasar/active galactic nucleus (AGN) population cannot provide enough photons to ionize the intergalactic medium (IGM) at z 6 unless the IGM is very homogeneous and the luminosity (L*1450) at which the QLF power law breaks is very low.",
author = "Linhua Jiang and Xiaohui Fan and James Annis and Becker, {Robert H.} and White, {Richard L.} and Kuenley Chiu and Huan Lin and Lupton, {Robert H.} and Richards, {Gordon T.} and Strauss, {Michael A.} and Sebastian Jester and Schneider, {Donald P.}",
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Jiang, L, Fan, X, Annis, J, Becker, RH, White, RL, Chiu, K, Lin, H, Lupton, RH, Richards, GT, Strauss, MA, Jester, S & Schneider, DP 2008, 'A survey of z ∼ 6 Quasars in the sloan digital sky survey deep stripe. I. A flux-limited sample at zAB < 21', Astronomical Journal, vol. 135, no. 3, pp. 1057-1066. https://doi.org/10.1088/0004-6256/135/3/1057

A survey of z ∼ 6 Quasars in the sloan digital sky survey deep stripe. I. A flux-limited sample at zAB < 21. / Jiang, Linhua; Fan, Xiaohui; Annis, James; Becker, Robert H.; White, Richard L.; Chiu, Kuenley; Lin, Huan; Lupton, Robert H.; Richards, Gordon T.; Strauss, Michael A.; Jester, Sebastian; Schneider, Donald P.

In: Astronomical Journal, Vol. 135, No. 3, 01.03.2008, p. 1057-1066.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A survey of z ∼ 6 Quasars in the sloan digital sky survey deep stripe. I. A flux-limited sample at zAB < 21

AU - Jiang, Linhua

AU - Fan, Xiaohui

AU - Annis, James

AU - Becker, Robert H.

AU - White, Richard L.

AU - Chiu, Kuenley

AU - Lin, Huan

AU - Lupton, Robert H.

AU - Richards, Gordon T.

AU - Strauss, Michael A.

AU - Jester, Sebastian

AU - Schneider, Donald P.

PY - 2008/3/1

Y1 - 2008/3/1

N2 - We present the discovery of five quasars at z 6 selected from 260 deg 2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the celestial equator. The five quasars with 20 < zAB < 21 are 1-2 magnitudes fainter than the luminous z 6 quasars discovered in the SDSS main survey. One of them was independently discovered by the UKIRT Infrared Deep Sky Survey. These quasars, combined with another z 6 quasar known in this region, make a complete flux-limited quasar sample at zAB < 21. The sample spans the redshift range 5.85 ≤ z ≤ 6.12 and the luminosity range -26.5 ≤ M 1450 ≤ -25.4 (H 0 = 70 km s-1 Mpc -1, Ωm = 0.3, and ΩΛ = 0.7). We use the 1/Va method to determine that the comoving quasar spatial density at 〈z〉 = 6.0 and 〈M 1450〉 = -25.8 is (5.0 2.1) × 10-9 Mpc-3 mag-1. We model the bright-end quasar luminosity function (QLF) at z 6 as a power law Φ(L 1450) L β 1450. The slope β calculated from a combination of our sample and the luminous SDSS quasar sample is -3.1 0.4, significantly steeper than the slope of the QLF at z 4. Based on the derived QLF, we find that the quasar/active galactic nucleus (AGN) population cannot provide enough photons to ionize the intergalactic medium (IGM) at z 6 unless the IGM is very homogeneous and the luminosity (L*1450) at which the QLF power law breaks is very low.

AB - We present the discovery of five quasars at z 6 selected from 260 deg 2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the celestial equator. The five quasars with 20 < zAB < 21 are 1-2 magnitudes fainter than the luminous z 6 quasars discovered in the SDSS main survey. One of them was independently discovered by the UKIRT Infrared Deep Sky Survey. These quasars, combined with another z 6 quasar known in this region, make a complete flux-limited quasar sample at zAB < 21. The sample spans the redshift range 5.85 ≤ z ≤ 6.12 and the luminosity range -26.5 ≤ M 1450 ≤ -25.4 (H 0 = 70 km s-1 Mpc -1, Ωm = 0.3, and ΩΛ = 0.7). We use the 1/Va method to determine that the comoving quasar spatial density at 〈z〉 = 6.0 and 〈M 1450〉 = -25.8 is (5.0 2.1) × 10-9 Mpc-3 mag-1. We model the bright-end quasar luminosity function (QLF) at z 6 as a power law Φ(L 1450) L β 1450. The slope β calculated from a combination of our sample and the luminous SDSS quasar sample is -3.1 0.4, significantly steeper than the slope of the QLF at z 4. Based on the derived QLF, we find that the quasar/active galactic nucleus (AGN) population cannot provide enough photons to ionize the intergalactic medium (IGM) at z 6 unless the IGM is very homogeneous and the luminosity (L*1450) at which the QLF power law breaks is very low.

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